Synergistic combination of flumetsulam with thiabendazole

ABSTRACT

A synergistic antimicrobial composition containing flumetsulam and thiabendazole.

This invention relates to combinations of biocides, the combinationshaving greater activity than would be observed for the individualantimicrobial compounds.

Use of combinations of at least two antimicrobial compounds can broadenpotential markets, reduce use concentrations and costs, and reducewaste. In some cases, commercial antimicrobial compounds cannot provideeffective control of microorganisms, even at high use concentrations,due to weak activity against certain types of microorganisms, e.g.,those resistant to some antimicrobial compounds. Combinations ofdifferent antimicrobial compounds are sometimes used to provide overallcontrol of microorganisms in a particular end use environment. Forexample, U.S. Pat. No. 5,591,760 discloses a combination of3-iodo-2-propynyl-butylcarbamate (IPBC) and4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT), but this referencedoes not suggest any of the combinations claimed herein. Moreover, thereis a need for additional combinations of antimicrobial compounds havingenhanced activity against various strains of microorganisms to provideeffective control of the microorganisms, especially in dry filmcoatings. The problem addressed by this invention is to provide suchadditional combinations of antimicrobial compounds.

STATEMENT OF THE INVENTION

The present invention is directed to a synergistic antimicrobialcomposition comprising: (a) flumetsulam; and (b) thiabendazole (TBZ);wherein a weight ratio of flumetsulam to thiabendazole is from 8:1 to1:15.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the following terms have the designated definitions,unless the context clearly indicates otherwise. Flumetsulam isN-(2,6-difluorophenyl)-5-methyl[1,2,4]triazolo[1,5-a]pyrimidine-2-sulfonamide.Diclosulam isN-(2,6-dichlorophenyl)-5-ethoxy-7-fluoro[1,2,4]triazolo[1,5-c]pyrimidine-2-sulfonamide.The term “antimicrobial compound” refers to a compound capable ofinhibiting the growth of or controlling the growth of microorganisms;antimicrobial compounds include bactericides, bacteristats, fungicides,fungistats, algaecides and algistats, depending on the dose levelapplied, system conditions and the level of microbial control desired.The term “microorganism” includes, for example, fungi (such as yeast andmold), bacteria and algae. The following abbreviations are usedthroughout the specification: ppm=parts per million by weight(weight/weight), mL=milliliter, ATCC=American Type Culture Collection,and MIC=minimum inhibitory concentration. Unless otherwise specified,temperatures are in degrees centigrade (° C.), and references topercentages are by weight (wt %). Percentages of antimicrobial compoundsin the composition of this invention are based on the total weight ofactive ingredients in the composition, i.e., the antimicrobial compoundsthemselves, exclusive of any amounts of solvents, carriers, dispersants,stabilizers or other materials which may be present.

Preferably, a weight ratio of flumetsulam to ZPT is from 8:1 to 1:12,preferably from 8:1 to 1:10, preferably from 7:1 to 1:12; preferablyfrom 7:1 to 1:10; preferably from 6:1 to 1:12; preferably from 6:1 to1:10; preferably from 6:1 to 1:8.

The antimicrobial compositions described above may contain otherbiocides. Typically, the antimicrobial compositions are used to inhibitgrowth of algae and/or fungi.

Preferably, the antimicrobial combinations of this invention areincorporated into liquid compositions, especially dispersions ofpolymers in aqueous media. The biocide combinations are particularlyuseful in preservation of building materials, e.g., adhesives, caulk,joint compound, sealant, wallboard, etc), paints, coatings, polymers,plastics, synthetic and natural rubber, paper products, fiberglasssheets, insulation, exterior insulating finishing systems, roofing andflooring felts, building plasters, wood products and wood-plasticcomposites. Preferably, the antimicrobial compositions are latex paintsor other liquid coating compositions containing the biocide combinationsdisclosed herein. The biocide combinations are useful for preservationof the dry film coating resulting after application of a paint or otherliquid coating composition. Preferably, the antimicrobial composition isan acrylic latex paint comprising one or more of the biocidecombinations disclosed herein, or the dry film coating resulting fromapplication of the paint to a surface.

Typically, the amount of the biocide combinations of the presentinvention to control the growth of microorganisms is from 100 ppm to10,000 ppm active ingredient. Preferably, the active ingredients of thecomposition are present in an amount of at least 300 ppm, preferably atleast 500 ppm, preferably at least 600 ppm, preferably at least 700 ppm.Preferably, the active ingredients of the composition are present in anamount of no more than 8,000 ppm, preferably no more than 6,000 ppm,preferably no more than 5,000 ppm, preferably no more than 4,000 ppm,preferably no more than 3,000 ppm, preferably no more than 2500 ppm,preferably no more than 2,000 ppm, preferably no more than 1,800 ppm,preferably no more than 1,600 ppm. Concentrations mentioned above are ina liquid composition containing the biocide combinations; biocide levelsin the dry film coating will be higher.

The present invention also encompasses a method for preventing microbialgrowth in building materials, especially in dry film coatings, byincorporating any of the claimed biocide combinations into thematerials.

EXAMPLES

Sample preparation: A single or blend of biocides was post added intowhite acrylic latex paint free of biocides to give a maximum totalactive ingredient/s concentration tested. This paint was then dilutedwith a biocide free acrylic latex paint to give targeted concentrationsfor the testing. Depending on the type of biocide blends tested, thetotal biocides concentrations varies from 200 to 5000 ppm. Afterbiocides addition or dilution, each sample was hand mixed for at least aminute until uniformity is achieved. Each of the paint samples as wellas a control sample (containing no biocide) were used to prepare filmson black plastic-vinyl chloride/acetate copolymer panels (LENETA,Mahwah, N.J.) using a 3 mil (0.0762 mm) bird bar applicator. The panelswere thoroughly dried for at least 2 days avoiding direct exposure tosunlight. Square discs (0.5 inch; 1.27 cm²) were cut out from each paneland were used as the substrate for fungal and algal efficacy tests. Thissample size allowed for an agar border when the sample disc was placedinto the well of the test plate. Each sample was tested in duplicate

Test Conditions:

The appropriate media (BOLD'S 3N for Chlorophytes, BG-11 forCyanobacteria, and PDA for fungi) were used to support microbial growth.The test plates were maintained at room temp (25° C.-26° C.), in acycled light-dark environment, for four weeks for algae. Plates forfungal challenge tests were maintained at 30 C for four weeks. At theend of the incubation period the samples were scored for percent areacovered by visible microbial growth.

Algal Inoculum

Medium for Organisms abbreviation Type testing Gloeocapsa sp. Gs ATCC29159 Unicellular, BG-11 Colonial Cyanobacteria Oscillatoria sp. Os ATCC29135 Filamentous BG-11 Cyanobacteria Nostoc commune Nc CCAP 1453/29Unicellular, Bold Cenobial Chlorophyte Trentepohlia aurea + Ta + To UTEXLB 429 + Filamentous Bold Trentepohlia odorata CCAP 483/4 ChlorophyteChlorella sp. UTEX + Cs + Ck ATCC 30582 + Unicellular Bold Chlorellakessleri ATCC 11468 Chlorophyte Calothrix parientina Cp UTEX LB 1952Filamentous Bold CyanobacteriaFungal Inoculum

Medium for Organisms abbreviation ATCC# Growth and Testing Aspergillusniger An 9642 PDA Penicillium funiculosum Pf 11797 PDA Cladosporiumherbarum Ch 11281 PDA Aureobasidium pullulans Ap 9348 PDA Trichodermaviride Tv 32630 PDA Alternaria alternata Aa 20084 PDAAlgal Efficacy TestingModified ASTM 5589

ASTM 5589 is a standard accelerated test method for determiningresistance of various coatings (including paints) to algal defacement.To accommodate for high-throughput screening, this method was scaleddown from petri plates to 6-well plates. A single coupon was placed witha pair of sterile forceps at the center of the agar plug (on top) withthe painted surface facing upwards. Algal inoculums were prepared bymixing equal concentrations (1×10⁶ cfu/ml) and equal volumes (dependingon number of samples to be inoculated) of like growing organisms.

In Flumetsulam+various IT synergy study, three pool of mixed algae wereprepared as the test inoculum, Gloeocapsa sp. and Oscillatoria sp. a mixof cyanobacteria grown on BG-11 media; Chlorella sp., Chlorellakessleri, and Nostoc commune are unicellular chlorphytes that were mixedand grown on Bold media; Trentepohlia aurea, Tretepohlia odorata, andCalotrix parientina are filamentous algae that were mixed and grown onBold media.

In Diclosulam+various IT synergy study, only two pools of mixed algaewere prepared; Gloeocapsa sp. and Oscillatoria sp. grown on BG-11 mediaand Chlorella sp., Chlorella kessleri, Nostoc commune, Trentepohliaaurea, Tretepohlia odorata, and Calotrix parientina grown on Bold media

Each well that contains a tested coupon was inoculated with 400 μl oforganism mixture (1×10⁶ cfu/ml) making sure that the whole surface(paint film as well as the agar surrounding it) was evenly covered. Theplates were incubated at room temp (25° C.-26° C.) with cyclic exposureto light (OTT-Lite model # OTL4012P, 40 Watt, 26 KLumen) and darkphases, for a period of four weeks. The total area covered was evaluatedat the end of each week according to percent area covered in 5%increments.

Fungal Efficacy Testing—Modified ASTM 5590

ASTM 5590 is a standard accelerated test method for determiningresistance of various coatings (including paints) to fungal defacement.To accommodate for high-throughput screening, this method was scaleddown from petri plates to 6-well plates. To set up the test, an agarplug was placed at the bottom of each well of the sterile 6-well plate.A single coupon was placed with a pair of sterile forceps at the centerof the agar plug (on top) with the painted surface facing upwards.Fungal inoculums were prepared by mixing equal concentrations (1×10⁶cfu/ml) and equal volumes (depending on number of samples to be tested)of like growing organisms. For Flumetsulam+various IT synergy study,three pools of mixed fungi were prepared as the test inoculum.Cladosporium herbarum was mixed with Aureobasidium pullulans;Aspergillus niger was mixed with Penicillium funiculosum and Alternariaalternata was mixed with Trichoderma viride. For Diclosulam+various ITsynergy study, all above fungi were mixed as a single pool. Each wellwas inoculated with 400 μl of organism mixture (1×10⁶ cfu/ml) makingsure that the whole surface (paint film as well as the agar surroundingit) was evenly covered. The plates were incubated at 30° C. in presenceof moisture, for a period of four weeks. The total percent area coveredwas evaluated and recorded at the end of each week after the 2^(nd) weekand recorded in increments of 5%.

Synergy Index Calculation

Synergy Index (SI)

The SI is calculated based on F. C. Kull et. Al. method (AppliedMicrobiology, Vol. 9 (1961). In this study, SI was calculated based onthe following formula with the minimum inhibitory concentration chosenbased on the percent inhibitory exhibited by the individual biocideagainst each microorganisms tested.SI=Qa/QA+Qb/QB

-   -   Qa=the concentration of Biocide A in the blend    -   QA=The concentration of Biocide A as the only biocide    -   Qb=The concentration of Biocide B in the blend    -   QB=The concentration of Biocide B as the only biocide SI value        of <1 in the formula indicates a synergism of the blended        biocides exists.

Flumetsulam: TBZ Synergy study Cp + Cs + AaTv AnPf ApCh To + Ta Ck + NcGs + Os 1Flumet: 1TBZ Total conc, 1000 1000 1000 4000 4000 2000 ppm %inhibition 100 100 100 40 100 90 SI <0.94 1.1 0.9 1.7 1.6 0.7 1Flumet:3TBZ Total conc, 1000 1000 1000 4000 3000 2000 ppm % inhibition 100.0100 100 90 100 90 SI <1.27 1.3 1.3 1.4 1.2 0.6 1Flumet: 5TBZ Total conc,900 900 900 3600 3600 900 ppm % inhibition 100 100 100 50 50 100 SI<1.24 1.3 1.2 1.1 1.4 0.3 1Flumet: 10TBZ Total conc, 962.5 962.5 962.53850 3850 2888 ppm % inhibition 100 90 100 40 40 90 SI <1.43 1.5 1.4 1.11.5 0.8 6Flumet: 1TBZ Total conc, 875 875 1750 3500 3500 875 ppm %inhibition 100 100 100 40 40 90 SI <0.41 0.7 0.8 1.9 1.3 0.3 4Flumet:1TBZ Total conc, 937.5 937.5 937.5 2813 3750 1875 ppm % inhibition 10090 100 80 70 90 SI <0.51 0.7 0.5 1.4 1.4 0.7 2Flumet: 1TBZ Total conc,937.5 37.5 3750 2813 3750 2813 ppm % inhibition 100 95 100 90 70 100 SI<0.68 0.9 2.7 1.3 1.5 1.0 Flumetsulam Total conc, 3500 1750 3500 17502625 2625 ppm % inhibition 0 90 50 75 100 90 TBZ Total conc, 625 625 6253750 2500 3750 ppm % inhibition 100 100 100 90 100 85 Note: If any ofthe active with maximum concentration tested did not exhibit someinhibition, this maximum concentration is used to calculate theestimated SI and a sign of less than (<) is included to take intoaccount that higher concentration of the active is needed to achieve thetargeted inhibition NE = no end point at the concentration tested thatwill meet the percent inhibition criteria set in each SI calculation

Synergy study of Diclosulam and TBZ Aa + Tv + An + Cp + To + Ta + RatiosPf + Ap + Ch Cs + Ck + Nc Gs + Os 1Diclosulam: 1 TBZ Total conc, ppm1500 3000 3000 % inhibition 60 100 100 SI 1.4 2.1 2.9 3Dicolosulam: 1TBZ Total conc, ppm 2250 3000 750 % inhibition 60 50 90 SI 1.4 1.9 1.85Diclosulam: 1 TBZ Total conc, ppm 300 3000 3000 % inhibition 50 80 100SI 1.5 1.8 4.1 10Diclosulam: 1 TBZ Total conc, ppm 2750 2750 687.5 %inhibition 50 80 95 SI 1.1 1.6 1.9 1Diclosulam: 10 TBZ Total conc, ppm3000 3300 825 % inhibition 50 80 90 SI 4.9 2.6 1.3 1Diclosulam: 6 TBZTotal conc, ppm 2800 2800 2800 % inhibition 50 95 100 SI 4.0 2.1 1.71Diclosulam: 4 TBZ Total conc, ppm 3250 3250 812.5 % inhibition 50 90100 SI 4.3 2.5 1.4 1Diclosulam: 2 TBZ Total conc, ppm 3000 3000 750 %inhibition 60 75 100 SI 3.5 2.2 1.5 Diclosulam Total conc, ppm 3500 1750875 % inhibition 0 100 90 TBZ Total conc, ppm 625 1250 1250 % inhibition60 100 85

The invention claimed is:
 1. A synergistic antimicrobial composition comprising: (a) flumetsulam; and (b) thiabendazole; wherein a weight ratio of flumetsulam to thiabendazole is from 6:1 to 1:10.
 2. The composition of claim 1 which is a building material.
 3. The composition of claim 2 in which the building material is a paint, coating, polymer, plastic, synthetic or natural rubber, paper product, fiberglass sheet, insulation, exterior insulating finishing system, roofing or flooring felt, building plaster, wood product or wood-plastic composite. 